/Engine/Source/Runtime/Core/Public/Templates/SharedPointer.h
Special constructor used internally to cast a 'const' shared reference a 'mutable' reference. You should never call this constructor directly. Instead, use the ConstCastSharedRef() function. This constructor creates a shared reference as a shared reference to an existing shared reference after const casting that reference's object. This constructor is needed for const casts.
template<typename OtherType> TSharedRef ( [TSharedRef](API\Runtime\Core\Templates\TSharedRef)< OtherType, Mode > const & InSharedRef, [SharedPointerInternals::FConstCastTag](API\Runtime\Core\Templates\FConstCastTag) )